A: Getting a top job in a company is not the same as getting a top job in a political party. You don't have to declare your candidacy and embark on a long and public election campaign. In fact, any sign that you're deliberately campaigning - or 'making your move' as you call it - could well do your chances more harm than good.
There's an element of hypocrisy in this, of course; some residual belief that well-brought-up English persons should know better than to reveal personal ambition; but there's good sense behind it as well. Two or more people clearly out to catch the eye of management for a job that hasn't even been declared vacant can have a hugely disruptive effect on a department. It can also, perversely, make management's decision more difficult; they won't want to be accused of taking the bait.
So my strong advice would be to carry on doing your job as you've always done it, to the best of your ability. Under no circumstances do anything that could be interpreted as increasing the pressure on your boss to quit. Only if and when her job becomes publicly available should you put in a brief, formal request to be considered for it. Resist the temptation to catalogue your many professional and personal qualifications; all that comes later.
If you're not offered the job your disappointment won't have to be public and, if you are offered the job and find yourself in charge of people older than yourself, your impeccable behaviour before your appointment should greatly lessen any potential resentment.